DETROIT -- The number of faces lined up at the left-field fence at Comerica Park for Tigers left-hander Matthew Boyd's bullpen session on Saturday afternoon would’ve suggested something seriously concerning. In fairness, his five-run, three-homer outing over just 2 2/3 innings on Thursday against the Royals was out of character enough to attract attention.

But many of the faces were from the Tigers analytics department. The eyes that mattered were the cameras on Boyd as he worked through his pitches. It’s an extension of the program the club implemented in Spring Training to study pitchers and gather enough information to detect trends.

“It’s just to accumulate data,” Boyd said. “Every single bullpen, we have it. So if something is ever out of whack, you can go, ‘Here’s the outlier.’”

Boyd wasn’t injured in Thursday’s thumping, just out of sync. The challenge was to figure out why.

The Tigers alternate the cameras they use. For one between-starts session, they’ll use an Edgertronics high-speed video camera. For the next turn, they’ll use a more standard view. They’ll also work in a Rapsodo machine. Add that data to the in-game information from Statcast and Trackman, and there’s a wealth of information from which to glean trends and suggest tweaks to his delivery.

“The only time it’s a teaching tool is if there’s something wrong, right? It’s more just data that we collect,” Boyd said. “You put it in and you see the norm and the averages.”

The Statcast data, at least, showed his slider wasn’t nearly as effective on Thursday. Boyd’s workhorse pitch drew 13 swings and misses, six foul balls and just two balls in play -- both with an exit velocity of 88.5 mph -- out of 39 pitches against the Rangers last weekend. On Thursday, the Royals swung and missed just four times out of 26 sliders with four foul balls. The four sliders put in play averaged 93.3 mph, topping out with a 105.5 mph home run from Cheslor Cuthbert.

By contrast, Boyd’s fastball drew way softer contact from the Royals -- an average 81.8 mph exit velocity -- than from the Rangers. But it also drew just three swings and misses and two called strikes out of 28 pitches. His curveball and changeup, meanwhile, were shrugged off.

While the spin rate on Boyd’s slider and fastball weren’t out of his ordinary range, according to Statcast, the vertical break was less than in previous starts. It was its lowest since June 26, the last time prior to Thursday that he allowed three home runs in a start.

The Royals have given Boyd plenty of trouble over the years, including two losses this season, but nothing quite like that. By contrast, Boyd handled the Mariners fairly easily in Seattle two weeks ago for 10 strikeouts over 6 1/3 innings of one-run ball. Unless Boyd goes on paternity leave -- his wife Ashley is due to give birth to their second child at some point in the next week -- he’ll get a rematch with the Mariners next week at Comerica Park.

Jackson staying in rotation

The Tigers called up Edwin Jackson on Friday to fill their need for an extra starter thanks to 11 games in a 10-day stretch that ends on Sunday. Not surprisingly, they’re sticking with Jackson after his 6 1/3 innings of one-run ball against the Royals.

Detroit isn’t going with a six-man rotation yet. For now, according to manager Ron Gardenhire, Tyler Alexander is headed to the bullpen, where he could pitch long relief in essentially a piggyback start. Drew VerHagen could do something similar. The Tigers could also need a fill-in start depending on when Boyd goes on paternity leave.

“We can do a lot of different things,” said Gardenhire, who emphasized nothing is set. “[General manager] Al [Avila] has left it up to us.”

Stewart still in concussion protocol

The sight of Christin Stewart in the Tigers' dugout near the end of Friday’s win raised hopes among fans that the slugging outfielder could be back from the concussion list on Saturday. Instead, though Stewart has returned from his rehab assignment, as he had a setback and will go through the concussion protocol again.

Quick hits

• Injured center fielder JaCoby Jones (left wrist contusion) and Jeimer Candelario (left thumb sprain) will undergo a CT scan on their injuries to make sure there’s no structural damage. Jones was out of the starting lineup for a second consecutive day on Saturday, while Candelario is on the 10-day injured list.

• Reliever Trevor Rosenthal, who was designated for assignment on Thursday, cleared waivers and elected free agency.

• Double-A Erie right-hander Alex Faedo, ranked as the Tigers’ No. 9 prospect by MLB Pipeline, was placed on the seven-day injured list on Saturday with a back strain. Faedo, the club's first-round pick in the 2017 MLB Draft, ranks second among Eastern League pitchers with 130 strikeouts over 112 1/3 innings, trailing only teammate Matt Manning.